Telephone system



Feb. 8, 1944. w. H. EDWARDS TELEPHONE SYSTEM Filed Sept. 11, 1940 2 Sheets-Sheet 1 INI/ENTOR W. H. ED WARDS Feb. 8, 1944. w. H. EDWARDS TELEPHONE SYSTEM Filed Sept. 11, 1940 2 Sheets-Sheet 2 STA T/O/V SETS TO OTHER KEY TELEPHONE TO OTHER KEY TELEPHONE STAT/0N SETS m RR m m0 VE H A T TOR/VEV Patented Feb. 8, 1944 TELEPHONE SYSTEM William H. Edwards, Great Neck, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application September 11, 1940, Serial No. 356,320

13 Claims.

This invention relates to telephone systems and particularly to improvements in subscribers telephone station equipment.

An object is to increase the usefulness of telephone sets, in general, and particularly to simplify the construction and manipulation of telephone station equipments for use in holding connections.

Heretofore mechanisms have been employed for holding a connection established while the subscriber is temporarily absent from the telephone. This has been accomplished, for example, by the use of mechanism for raising the switchhook while the receiver remains on the switchhook or by a push-button associated with a handset telephone stand for holding the line engaged.

A feature of the present invention relates .to the holding arrangement for subscribers telephone sets consisting of a relay and special contacts controlled by a button so arranged that when the handset is removed from the cradle a shunt circuit is closed to prevent the relay from operating. When the button is thereafter manually operated, the shunt is removed, 'and the relay is included in a circuit and operates to close a holding circuit across the line, the handset may then be replaced. On the second removal of the handset the shunt circuit is again established, and the relay releases to open the holding circuit.

Another feature is the arrangement whereby in case a plurality of subscribers stations are associated with a single line, such as a main station and one or more extension stations, a common relay is provided for the holding of the line. The arrangement of the circuits are such that, when the main station subscriber replaces his handset on the cradle after having operated the relay to hold the connection, the connection may then be picked up by any one of the extension stations by the removal of the associated handset and the consequent release of the common relay to open the holding circuit.

Another feature is an arrangement whereby in case one or more subscribers stations are each equipped with keys for establishing con-- scriber also has access. The holding condition of the first line may then be released by the removal of the handset at either of the stations involved.

The invention has been illustrated in the accompanying drawings in which Fig. 1 shows a side view of a subscriber's telephone stand with a portion broken away to show the details of applicant's invention inside the stand.

Figs. 2, 3 and 4 show various positions of the special arrangement of the plunger and contacts in accordance with the applicant's invention.

Fig. 5 is a circuit diagram of a line and two subscribers stations connected thereto and arranged in accordance with the applicant's invention.

Fig. 6 is a circuit diagram of a two-line key telephone system arranged in accordance with a modified form of the applicant's invention.

Referring now to the drawings, Fig. 1 shows a housing I of an ordinary standard subscribers telephone stand with a handset 2, partly in section, resting in the usual cradle to maintain the usual two plungers in a normal position, one of these plungers has been shown marked 3 while the other is notshown in this figure but is located directly behind plunger 3. Plunger 3 operates on a lever A and the other on a similar lever forming part of a cradle member 5 having an extension 6 so arranged that when the handset is resting in the cradle, the plungers will operate on these levers to maintain a series of contacts marked 1 in a normal position to disconnect the subscribers telephone circuit from a line. A diagrammatic representation of these elements is shown in Fig. 5. When the handset 2 is removed from the cradle, the plungers will be moved upward by the tension of springs 1 for a short distance, for example, as shown in Fig. 2, for plunger 3 to permit springs 1 to connect the telephone circuit to a line. On one plunger, namely plunger 3, is provided a special extension I II on which is located a floating cam or bushing ll held in its lower position by a pin l2 and slidable on the extension Ill. The purposes of this bushing is to operate on contacts II when the plunger 3 is raised manually after the handset is removed from the cradle to the position as shown in full in Fig. 3. When the bushing H engages one of the contacts [4 to separ atethem this raising of the plunger 3 to this 'ip'osition will not effect the lever 4. as the lever 'l extends through a slot Hi to permit this upwardmovement of plunger 3. After the plunger 3 has been moved to this upward position, and then released, it may drop back in the position shown in dotted line in Fig. 3 while the bushing ll remains in engagement with springs l4 as the bushing I1 is slidable on the extension In. However, when the handset is replaced in the cradle, both plungers will be restored to normal position. Plunger 3 is shown partially restored in Fig. 4 and in this position it is shown, how the shoulder ll of the plunger 3 will engage the bushing ll to disengage it from the springs -l4. The position of the plunger, bushing and springs in this Fig. 4 are shown just before the bushing is in position to release the springs. The arrangement should be such that the lever 4 in this position will be engaged by the plunger 3 to open the connections between the contacts in the group 1 before the connections between the contacts l4 are closed, the purpose of which will be described hereinafter in connection with the circuit diagram in Fig. 5. Thus the plunger 3 may be used as a means for causing a connection to be held even though the handset is replaced on the cradle.

The operations to produce this effect may be as follows and may be described in connection with the circuit in Fig. 5. In this figure two subscribers stations and 2| have been shown connected to a single line 23. If it is assumed that the subscriber at station 20 removes the handset 2 from the cradle, the contacts 1 will be closed and establish a circuit for the transmitter and receiver through the usual induction coil and subscriber circuit arrangement, as is well-known in the art. This is accomplished through the two left hand sets of contacts, while the-right hand set of contacts 26 close a shunt circuit for the relay 21. The line 23 is now closed from the tip conductor through the induction coil 25 and the transmitter circuit to the point 28, the middle contacts, contacts 26 and contacts i 4, to the ring conductor of line 23. Thus the telephone circuit may be connected to the line normally without operatin the relay 21. In case the subscriber now desires to leave his telephone and yet maintain the connection to the central ofllce established, even though he replaces the handset in the cradle, he may do so by proceeding as follows. The subscriber, first operates the plunger 3 upward to the position as shown in Fig. 3 to open the connection at contacts l4. This opens this short circuit for relay 21 which now operates over a circuit established from the tip conductor, induction coil 25, the transmitter circuit to point 28, the middle contacts of the group 1, winding of relay 21 to the ring conductor. Relay 21 in operating closes a locking circuit for itself from the tip conductor through the resistance 30, the armature and front contact of relay 21, winding of this relay to the ring conductor. central oillce is therefore maintained as long as relay 21 is maintained energized and locked. The subscriber may now replace his handset in the cradle, which opens the contacts 1 and restores the connection between contacts l4 in a manner described in connection with Fig. 4. That is, the contacts 26 of the group 1 will open before the connection between contacts I4 is closed so as not at this time to short-circuit the winding of relay 21 which would happen if contacts l4 were closed before contacts 26 were opened. When the same subscriber or another at either station 20 or 2| removes the handset from the cradle and thus again closes the connection at contacts 1 The connection to the or the equivalent contacts of station 2|, assuming that this occurs at station 20, the connection between contacts I4 is closed and contacts 26 willshort-circuit the relay 21 which will now release and open the locking circuit through its armature and front contact and resistance 3|. Then after the subscriber has finished the conversation, he may return the handset on the cradle and then the relay will be releasedas usual.

It is evident that a subscriber at station 2| may proceed in the same manner as the subscriber at station 20 to hold the line engaged by operating his plunger 3 and contacts l4 in the same manner to operate relay 21. A plurality of subscribers' stations on the same line may therefore employ a single locking relay 21 for holding the line engaged and permitting the removal of bolding by either one of the stations. It should be noted that relay 21 is at no time in circuit except under holding conditions and does not introduce transmission loss in the line, unbalanceor short conductor loop limits from a pulsing. tripping or supervisory standpoints, as it is shunted under all of these conditions.

In Fig. 6 is shown an adaptation of this same circuit arrangement to a key telephone system having two lines and a number of stations. In this case the telephone station 40 is identical with stations 20 or 2| but equipp d with keys 42 and 43 for connecting it to lines 44 or 45. These lines in turn may be multipled to other stations such as station 50 indicated by a box. and equipped the same as station 40. Line 44 is provided with a relay 46 and line 45 is provided with relay 41 connected in the same manner in the circuit as is relay 21 in Fig. 5. In this modifled form of the applicant's invention, if for example the subscriber of station 40 desires to connect with line 44, he will operate key 42 and if he then desires to hold this line, he will operate the plunger 3 to open contacts l4 and thereby cause relay 46 to operate and hold this line, in the same manner as the subscriber manipulates his plunger 3 in connection with stations 2|! or 2|, whereupon he can replace the handset and leave the station. He is then free to answer a call or call line 45 from another station, for example station 50. If he then desires to again take up the connection with line 44 he can do so by merely removing the handset at station 40 and thereby release relay 46. On the other hand if he does not desire to again pick up the line 44 at station 40 but wants to release this line. he will operate key 43 at the station 40 so that when he removes the handset at the other station 50 over which he is making a call or is being called, he will release line 44 by short-circuit relay 46 through the circuits at this other station 50 in the usual manner. Similarly a line may be released by any station associated in this system.

What is claimed is:

1. In a subscriber's telephone set including a receiver, a line circuit connected to said set, and means associated with said set controllable for closing the line circuit through said set in response to the removal of the receiver from the set, and contact and circuit means for closing said line circuit independent of the set and for maintaining it closed after the receiver is replaced, said first-mentioned means being thereafter effective to disable said contact and.circuit means in response to the subsequent removal of the receiver.

2. In a subscriber's telephone set, including aholder for the receiver, a line circuit connected to said set and means associated with said set controllable to close the line circuit through said set in response to the removal of the receiver from the holder, and contact and circuit means for closing the line circuit independent of the set and for holding said circuit closed independent of the set after the receiver has been replaced on the holder, said first-mentioned means being thereafter efiective to disable said contact and circuit means in response to the subsequent removal of the receiver from the holder.-

3. In a subscribers telephone set including a receiver, a line. a relay, a circuit for closing said line independent of the telephone set by the operation of said relay,. and means for operating said relay operative after the receiver is removed from the set and for releasing said relay in response to the replacing and subsequent removal of the receiver from the set.

4. In a subscriber's telephone set, a stand, a handset. a cradle therefor in said stand, a relay. switching contacts normally open and controllable by the removal of the handset from the eradle to close said switching contacts, a button in said stand, contacts normally closed and controllable manually by the operation of said button after the handset is removed from the cradle for opening said contacts. a circuit controlled by said two sets of contaetsto permit the said relay to operate when the handset is removed and the button is operated manually-and to hold said relay operated when the handset is replaced and to release said relay when the handset is subsequently removed.

5. In a subscribers telephone set, a desk stand, a handset, a cradle therefor, a line, a relay, an energizing circuit for said relay, a shunt circuit for said energizing circuit, means for closing said line through said telephone set and for closing said energizing circuit and said shunt circuit to prevent the operation of said relay in response to the removal of the handset from the cradle, means for thereafter opening said shunt circuit to permit the operation of said relay by said energizing circuit, a circuit controlled by said relay when energized for locking said relay across the line and shunt said telephone set, so that on the replacing of the handset on the cradle, the opening of the energizing circuit and shunt circuit will not cause the relay to release, and so that on the subsequent removal of the handset from the cradle and when the shunt circuit is closed said relay will release.

6. In a subscriber's telephone set. a line, a handset. a cradle for said handset, a relay, switching contacts normally open and operative to close in response to the removal of the handset from the cradle, a button, contacts normally closed and operative to open in response to the removal of the handset from the cradle and to the manual actuation of the button, circuits for said two sets of contacts and said relay, controlled by said switching contacts when the handset is removed from the cradle to connect said line to said telephone set and to close an energizing path switching contacts on the subsequent removal of the handset from the cradle to close said energizing path and said shunt path to permit the release of the relay and a locking circuit for said relay operative to lock said relay across the line when said relay is operated so as to maintain it operative while the handset remains replaced in the cradle and the energizing path and shunt path are open.

'7. In a subscriber's telephone set, a line, a handset, a cradle for said handset, a relay. switching contacts normally open and operative in response to the removal of said handset from the cradle, a button, contacts normally closed and operative to open in response to the removal of the handset from the cradle and to the manual raising of said button, said button being so constructed that on the restoringof the button to normal in response to the replacing of the hand set on the cradle after it has been manually raised, said last-mentioned contacts are closed after the opening of the switching contacts, circuit means controlled by said two sets of contacts to prevent said relay from operating when the handset is removed and the button is first raised and to hold said relay operated when the handset is replaced and to release said relay when the handset is again removed.-

8. In a telephone system, a line, a plurality of subscriber's telephone stations connectable to said line, means associated with each station for closing said line through a station responsive to the removal of the receiver from its holder at said station, and means associated with said line for thereafter holding the line engaged independent of said station after the receiver has been re-'- placed and means operative to open said independent holding connection responsive to the subsequent removal of the receiver at any one of said stations.

9. In a telephone system, a line, a plurality of subscribers stations connectable to said line, means associated with each station for closing said line through a station in response to the removal of the receiver from its holder at said sta tion, a relay associated with said line, a circuit for closing said line independent of any station by the operation of said relay, means for actuating said relay operative after the receiver has been removed at a station and means for releasing said relay in response to the replacement of a receiver and a subsequent removal of the receiver at any one of said stations.

10. In a telephone system, stations, keys at each station, a plurality of lines terminating in said stations for connection to said stations by the operation of corresponding keys, means responsive to the operation of a key at a station and the removal of the receiver from its holder thereat for closing the corresponding line through the telephone station, means associated with each line operative to close an independent connection across the associated line to hold it after said line has been connected through a station and operative prior to the replacing of the receiver at that station and means for opening said independent connection responsive to the subsequent removal of the receiver at said connected station.

11. In a telephone system, stations, keys at said stations, a plurality of lines terminating in said stations for connection to said stations by the operation of corresponding keys, means responsive to the operation of a key at a station and the removal of the receiver from the holder thereat for closing the corresponding line through the telephone station, means associated with each line operative to close an independent connection across the associated line to hold it after said line has been connected through a station and operative prior to the replacing of the receiver at that station and means for opening said independent connection responsive to the replacing of the receiver and subsequent removal of the receiver at said connected station or responsive to the replacing of the receiver and the subsequent removal of the receiver at any other station it it had been connected to said line by the operation 01 the corresponding key.

12. In a telephone system, stations, keys at each station, a plurality of lines terminating in said stations for connecting to said stations by the operation of corresponding keys, means responsive to the operation of a key at a station and the removal of the receiver from its holder thereat for closing the corresponding lines through the telephone station, a relay associated with each line, a circuit for closing a connection across a linein response to the operation of the associated relay. means for operating the relay of a line after it has been connected to a station by an associated key and if said line has been closed through said station by the removal of the receiver thereat and means for releasing said relay to open said connection responsive to the replacing or the receiver and the subsequent removal of the receiver at said station.

13. In a telephone system, stations, keys at each station, a plurality of lines terminating in said stations for connecting to said stations by by an associated key and it said line has been WILLIAM H. EDWARDS. 

